Inductorium

Electromagnetic induction machine, the object of which is to obtain high electromotive force by making use of a source of large quantity but of comparatively low electromotive force; invented by Dr. Page and improved by Ruhmkorff; hence sometimes called Ruhmkorff's coil. It consists of a primary coil of thick insulated wire and few windings, in the center of which is a core of soft iron wires. Outside of this is the secondary coil, of fine wire and very many turns. The primary coil is connected with the source of current, and in the circuit is an interrupter. Thus an intermittent current of high electromotive force is in Ruhmkorff's Coil. duced in the secondary coil. An important addition to the apparatus, made by Fizeau, is the condenser, which is connected on the two sides of the interrupter: its function is to prevent the spark of the extra current in the primary when the circuit is broken. Instruments have been constructed which will give a spark a meter or more in length.